Credible options for UK plutonium disposal

Both the Prism and Enhanced Candu 6 (EC6) reactors are "credible options" for managing the UK's plutonium stockpile, the Nuclear Decommissioning Authority (NDA) has concluded. However, the government's preferred option remains reuse as mixed-oxide (MOX) fuel.

In early 2012, the NDA invited expressions of interest on potential alternative credible full lifecycle management options for managing the UK's plutonium stockpiles. The use of plutonium in MOX fuel had earlier been selected as the preferred route by the government. Four responses were received and the NDA shortlisted two of them - GE-Hitachi Nuclear Energy's Prism reactor and Candu Energy's Enhanced Candu 6 (EC6) reactor - for further consideration.

Candu's EC6 (Image: Candu)

The NDA has now concluded that the Prism and EC6 reactor are also "credible reuse options" and said that it will continue to examine these options in the next stage of its work. However, it noted that both reactors "have some benefits as well as disadvantages when compared to the reference LWR MOX option."

"Currently, we believe there is insufficient understanding of the options to confidently move into implementation," the NDA concluded. It plans to undertake technical studies over the next 1-2 years "to establish a consistent level of understanding of risks and uncertainties for each option." The NDA noted that no "perfect" solution exists and that a "multi-track approach" may offer the best value for money.

Options for implementing a commercial procurement process are being developed, the NDA said, but "the form of this can only be defined once market positions are better understood." The organization said that it will "establish approaches to cover both a competitive and sole provider condition." It also intends to work on regulatory and licensing aspects with the technology vendors and UK regulators to "define licensing needs and understand deployment risks such as fuel performance demonstration, noting this is a significant risk area for all options."

Prism (Image: GE-Hitachi)

Candu's proposal centres on the deployment in the UK of its Enhanced Candu 6 (EC6) reactor and associated facilities. Joint Canadian and Chinese research has already demonstrated the ability of the heavy-water moderated and cooled reactor to use alternate fuels and for the recycling of MOX. The EC6 reactor is an evolution of the Candu 6 reactor.

GE-Hitachi's proposal relates to the deployment of its Prism reactor design as part of an integral fuel fabrication and reactor facility. The company has been active in promoting its proposals for a small power plant where two of the 311 MWe fast reactors would irradiate fuel made from the UK's plutonium stocks, bringing it to a form suitable for disposal.

The UK currently has about 100 tonnes of plutonium - the largest national stockpile worldwide - that has been separated during the reprocessing of used nuclear fuel over several decades. Once reprocessing of AGR fuel has been completed around 2018, this amount is expected to total some 140 tonnes. The NDA noted, "This is a long term program with bulk reuse of plutonium likely to commence around 2030-2035 and concluding several decades after that."